Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754960Ab3CEWKN (ORCPT ); Tue, 5 Mar 2013 17:10:13 -0500 Received: from mail-ee0-f43.google.com ([74.125.83.43]:54145 "EHLO mail-ee0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751921Ab3CEWKL (ORCPT ); Tue, 5 Mar 2013 17:10:11 -0500 Message-ID: <51366D3E.2050903@suse.cz> Date: Tue, 05 Mar 2013 23:10:06 +0100 From: Jiri Slaby User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:19.0) Gecko/20130124 Thunderbird/19.0 MIME-Version: 1.0 To: Peter Hurley CC: jhovold@gmail.com, Greg Kroah-Hartman , Alan Stern , USB list , linux-serial@vger.kernel.org, Alan Cox , LKML Subject: Re: [Fwd: [PATCH v2 0/4] TTY: port hangup and close fixes] References: <1362085054.3337.20.camel@thor.lan> <51361724.4050107@suse.cz> <1362503170.18799.33.camel@thor.lan> <51366A29.2060808@suse.cz> <1362520976.18799.134.camel@thor.lan> In-Reply-To: <1362520976.18799.134.camel@thor.lan> X-Enigmail-Version: 1.6a1pre Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1720 Lines: 49 On 03/05/2013 11:02 PM, Peter Hurley wrote: > On Tue, 2013-03-05 at 22:56 +0100, Jiri Slaby wrote: >> On 03/05/2013 06:06 PM, Peter Hurley wrote: >>>>> @@ -225,15 +232,13 @@ void tty_port_hangup(struct tty_port *port) >>>> spin_lock_irqsave(&port->lock, flags); >>>> port->count = 0; >>>> port->flags &= ~ASYNC_NORMAL_ACTIVE; >>>> - if (port->tty) { >>>> + if (port->tty) >>>> set_bit(TTY_IO_ERROR, &port->tty->flags); >>>> - tty_kref_put(port->tty); >>>> - } >>>> - port->tty = NULL; >>>> spin_unlock_irqrestore(&port->lock, flags); >>>>> + tty_port_shutdown(port, port->tty); >>>> >>>> What prevents port->tty to be NULL here already? >>> >>> Nothing. That's why it's tested in tty_port_shutdown() above. >> >> I know :). > > Sorry :) > >> But the question is rather don't we want to pass the real >> refcounted port->tty (take a snapshot inside the lock) instead? > > I think that's why he moved the kref release to after the shutdown (via > tty_port_set_tty()) -- but I'm tired and maybe I'm missing something > here? port->tty can be changed right after the unlock. So I'm thinking about something like this: if (port->tty) set_bit(TTY_IO_ERROR, &port->tty->flags); tty = port->tty; <=== take a snapshot spin_unlock_irqrestore(&port->lock, flags); tty_port_shutdown(port, tty); <=== use the snapshot set_tty_port(port, NULL); <=== put kref on that tty -- js suse labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/